Large industrial electrical equipment, such as oil-filled pad mounted transformers, load tap changers, and the like, contain contacts and other parts which can wear out over time. Since these parts are located inside an oil-filled tank, it is very difficult to visually inspect them. Instead, dissolved gas analysis is often used to measure the level of “fault gases” in the oil. The level of fault gases may be used to estimate the condition of the equipment. However, dissolved gas analysis requires an oil sample to be taken from the transformer tank. Typically, the oil sample would be taken from a valve located on the tank within the transformer cabinet. Because the valve is inside the cabinet, alongside exposed electrical contacts, the transformer would need to be de-energized before the sample was taken to avoid the risk of injury or death to the person taking the sample. De-energizing a transformer is costly. What is needed is an apparatus that will allow a user to safely obtain an oil sample from electrical equipment without having to de-energize the equipment. The apparatus is preferably also tamper resistant.